Method of joining metal-ceramic substrates to metal bodies

Abstract

A method of joining a metal-ceramic substrate having metallization on at least one side to a metal body by using metal alloy is disclosed. The metal body has a thickness of less than 1.0 mm and the metal alloy contains aluminum and has a liquidus temperature of greater than 450° C. The resulting metal-ceramic module provides a strong bond between the metal body and the ceramic substrate. The resulting module is useful as a circuit carrier in electronic appliances, with the metal body preferably functioning as a cooling body.

What is claimed is: 
     
       1. A method of joining a metal-ceramic substrate to a metal body using a metal alloy, where the metal-ceramic substrate has metallization on at least one side, the method comprising:
 providing the metal body with a thickness of less than 1 mm; 
 placing a metal alloy which contains aluminum and has a liquidus temperature of greater than 450° C. between the metal-ceramic substrate and the metal body to form an assembly, wherein the metal-ceramic substrate is adapted to have a semiconductor component disposed on at least one metalized side of the metal-ceramic substrate, and wherein the metal-ceramic substrate includes a ceramic substrate and no more than two metal layers; and 
 heating the assembly to a temperature of greater than 450° C. such that the at least one metalized side of the metal-ceramic substrate contacts an inert gas atmosphere during heating. 
 
     
     
       2. The method of  claim 1 , wherein the metal alloy further comprises silicon. 
     
     
       3. The method of  claim 1 , wherein the metal alloy further comprises magnesium. 
     
     
       4. The method of  claim 1 , wherein based on the total weight of the metal alloy, the metal alloy contains more than 50.0% by weight of aluminum. 
     
     
       5. The method of  claim 1 , wherein the metallization on the metal-ceramic substrate is on a side of the metal-ceramic substrate facing away from the metal body. 
     
     
       6. The method of  claim 5 , wherein the metallization comprises copper. 
     
     
       7. The method of  claim 5 , wherein the metallization comprises aluminum. 
     
     
       8. The method of  claim 1 , wherein the assembly is at least partly coated with at least one of nickel, gold, and silver. 
     
     
       9. The method of  claim 1 , wherein the metal body comprises aluminum. 
     
     
       10. The method of  claim 1 , wherein a ceramic portion of the metal-ceramic substrate comprises at least one of aluminum oxide, silicon nitride, and aluminum nitride. 
     
     
       11. The method of  claim 1 , wherein the metal body comprises at least one of AlSiC, MoCu, WCu, CuMoCu, and Cu/Invar/Cu. 
     
     
       12. The method of  claim 1 , wherein a side of the metal-ceramic substrate facing the metal body is smaller than a side of the metal body facing the metal-ceramic substrate. 
     
     
       13. A module comprising:
 (a) arranging a metal alloy between a metal-ceramic substrate and a metal body having a thickness of less than 1 mm, wherein an upper surface of the metal alloy contacts a lower surface of the metal-ceramic substrate, wherein a lower surface of the metal alloy contacts an upper surface of the metal body, wherein the metal alloy comprises aluminum, wherein the metal alloy has a liquidus temperature of at least 450° C., wherein the metal-ceramic substrate is adapted to have a semiconductor component disposed on at least one metalized side of the metal-ceramic substrate, and wherein the metal-ceramic substrate includes a ceramic substrate and no more than two metal layers; and 
 (b) bounding the metal-ceramic substrate to the metal body such that a peel force for separating the metal-ceramic substrate from the metal body exceeds 3 N/mm, and such that the at least one metalized side of the metal-ceramic substrate contacts an inert gas atmosphere during bonding. 
 
     
     
       14. The method of  claim 13 , wherein the peel force exceeds 3 N/mm without using a screw, clamp, or Thermal Interface Material (TIM) to fasten the metal-ceramic substrate to the metal body. 
     
     
       15. The method of  claim 13 , wherein the bonding of (b) involves heating the metal-ceramic substrate, the metal alloy, and the metal body arranged in (a) to a temperature greater than 450° C. 
     
     
       16. The method of  claim 13 , wherein the metal body comprises aluminum. 
     
     
       17. The method of  claim 13 , wherein the metal alloy comprises aluminum, and wherein the metal alloy is 50.0% by weight aluminum. 
     
     
       18. The method of comprising:
 (a) placing an assembly onto a conveyor belt of a furnace having a plurality of heating zones, wherein the assembly comprises a substrate, a first metal layer, and a second metal layer having a thickness of less than 1 mm, wherein the substrate is disposed above the first metal layer such that a lower surface of the substrate contacts an upper surface of the first metal layer, wherein the first metal layer is disposed above the second metal layer such that a lower surface of the first metal layer contacts an upper surface of the second metal layer, wherein the first metal layer comprises aluminum and has a liquidus temperature of at least 450° C., wherein at least one metalized side of the substrate is adapted to receive a semiconductor component, and wherein the substrate includes a ceramic substrate and no more than two metal layers; 
 (b) heating the assembly through the plurality of heating zones of the furnace such that the at least one metalized side of the substrate contacts an inert gas atmosphere during heating, wherein the assembly is heated from between 580° C. to 650° C.; and 
 (c) cooling the assembly to room temperature. 
 
     
     
       19. The method of  claim 18 , wherein the steps of (a), (b), and (c) cause the substrate to be bonded to the second metal layer such that a peel force for separating the substrate from the second metal layer exceeds 3 N/mm. 
     
     
       20. The method of  claim 19 , wherein the peel force exceeds 3 N/mm without using a screw, clamp, or Thermal Interface Material (TIM) to fasten the substrate to the second metal layer. 
     
     
       21. The method of  claim 1 , wherein the joining of the metal-ceramic substrate to the metal body results in a circuit carrier.